A PDP displays images by exciting a phosphor substance with ultraviolet light generated by gas discharge for light emission.
A PDP is roughly classified into the AC type and DC type by driving method, and the surface-discharge type and opposed-discharge type by discharging method.
In terms of moving to finer-resolution, an increase in the screen size, and easiness in manufacturing owing to simplicity of the structure, a PDP nowadays prevails with a three-electrode structure and the surface-discharge type.
A PDP is composed of a front panel and a back panel. The front panel has display electrodes including scanning electrodes and sustain electrodes; a dielectric layer covering the display electrodes; and a protective layer further covering the dielectric layer, on a substrate made of glass or the like. The back panel has a plurality of address electrodes orthogonal to the display electrodes, a dielectric layer covering the address electrodes, and partition walls on the dielectric layer. Arranging the front panel and the back panel facing each other forms a discharge cell at the intercept of the display electrode and the data electrode, where the discharge cell has a phosphor layer.
Such a PDP offers high-speed display as compared with a liquid crystal panel. In addition, it features a wide viewing angle, easy upsizing, and a high-quality display owing to its self-luminous property, attracting attention among flat-panel displays. It is widely used in various applications, particularly for a display device in a public place where many people gather, and for enjoying a large-screen image at home.
In a PDP, for example, a display electrode and address electrode require a relatively high accuracy in their shapes and allocation pitches.
Therefore, so-called photolithography is used, where the whole surface of the substrate is coated with a conducting material such as a metallic material, containing a photosensitive material, which is exposed and developed using a photomask with an electrode pattern. A method for forming an electrode with a predetermined shape at a predetermined position of a substrate using a lithographic process is introduced in, for example, the 2001 FPD Technology Outlook (Electronic Journal, Co., Oct. 25, 2000, pp. 589-594, pp. 601-603, and pp. 604-607).
Here, the photosensitive material hardens with a cross-linking reaction due to an exposure, and an overexposure may occur depending on its exposure conditions. In such a case, the cross-linking reaction proceeds excessively, causing the electrode film to indwell a stress. Baking under this condition may contract the electrode film, causing retroflexion and exfoliation on the edge of a pattern for a structure such as an address electrode, of a PDP. This is an example for an electrode. In a PDP, despite its large screen, a structure other than an address electrode also requires accuracy. Consequently, photolithography may be used to form a structure, such as a partition wall, other than an electrode. Such a case may also cause the problems as mentioned above in image display.
These problems may adversely affect a display image.